Recently, as further miniaturization of large scale integrated circuits (LSI) proceeds, a technology for processing a more delicate structure is demanded. In response to such demand, an attempt has already been started in which a fine pattern is formed using a phase-separated structure formed by self-assembly in a block copolymer containing two or more blocks are independent each other and are mutually bonded (see for example, Patent Document 1).
For using a phase separation structure of a block copolymer, it is necessary to form a self-assembly nano structure through a microphase separation only in desired regions, and arrange the nano structure in a desired direction. To achieve a desired structure having desired position and orientation, graphoepitaxy to achieve desired phase-separated pattern by a guide pattern and chemical epitaxy to achieve desired phase-separated pattern by difference in the chemical state of the substrate are proposed (see, for example, Non-Patent Document 1).
In chemical epitaxy process, a neutralization film having a predetermined pattern is disposed on the surface of a substrate, the neutralization film has affinity to any of the blocks constituting the block copolymer and contains a surface treatment agent. By virtue of the pattern of the neutralization film (i.e., guide pattern) on the surface of the substrate, the orientation of each phase of the phase-separated structure is controlled. Therefore, to form a predetermined phase-separated structure, it is important that the neutralization film is disposed in accordance with the period of a block copolymer.
As the block copolymer, a block copolymer (PS-b-PMMA) containing a block composed of a repeating unit of styrene and a block composed of a repeating unit of methyl methacrylate have been widely studied. It is considered that the PS-b-PMMA is a material applicable to the formation of the fine pattern of about 13 nm.
Recently, research is also being conducted into a method of forming a pattern in which an Si-containing block copolymer is used as a material capable of forming a pattern having a further micro dimension. The block copolymer layer formed from the Si-containing block copolymer has a low surface energy. Therefore, for the self-assembly technique in the block copolymer, it is important to optimize the surface condition of the block copolymer layer.